Renewable fuse



Feb. 19 i924.

L. B. BUCHANAN RENEWABLE FUSE Filed Sept. '7 1920 the locking nut Puentes ret. 19', 41924.

Laominn n. Booman, or wcnoamxasacnusn'r'rs, Assioma 'ro 'ma cnam' SHAWIUT COIPANY, E BOBTONIASSACHUSETTS, A CORPORATION OF KASSA- aBLn rusa CHUBETTS.

Appnuen med september 7, 1920. serial 110.408,448.

Toallwhomitmayconcem:

Be it known that 1,. LEONA@ B. BU- CHANAN, a citizen of the United States, residing at Woburn,in the county of Middlesex and State of Massachusetts, have invented an Improvement in Renewable Fuses, o t

which the following is a specification.

This invention relates to a renewable 'enclosed electric fuse of the cartridge type.'

especially desi ed for u'se 'with fuse termi,- nals of the knife-blade type and has for its object tion and ease of ment of the fuse.

renewing the' fusible ele- Fig. 1 is a side elevation lof a fuse embody inv' my invention.

`ig. 2 is a longitudinal sectional elevation of the fuse of Fig. 1.

Fig. 3 is an en view of the fuse.

Fig. 4 is a view similar to Fig. 3 but with removed.

Fig. 5 is an end view of the fuse with the locking nut and end-.cap removed.

Fig. 6 is a plan view of a knife-blade fuse terminal.

Fig. 7 is a view of the inner end of the knife-blade plug, particularl illustrating the staggered arrangement o the gas pasp with the interior recess 1n its body-porl sa es therethrough.

ig. 8 is an enlar d sectional detail of one end of the fuse with the fuse components in assembled position. As here shown, the fuse comprises the usual tubular enclosing casinglO of insulating material having the exteriorly threaded ferrules 11-11 on its ends. A thin metal ring'12 is received within the casing at each end and is formed with two internal, diametrically-opposed struck-out portions or projections 12* which extendl longitudinally within the casing and form internal guides adapted to be engaged by plugs forming parts of the contact blades and prevent rotation thereof. Said rings and ferrules may be secured t0 the casing by the rivets 11* passed through all of said components. The fusible element is extended longitudinally within the casing and includes the fuse strip 13 of'zinc or other appropriate material and the contact blades 14 renewably secured at itsends by the bolts 15. v

Said contact bl'adesare formed of strips, preferably of copper, havmg reduced endto improve the construction, opera- -gu audits contact blade will b e retained against rotation-in said casing. Said plug is formed for a' substantial distance portions 14* to which the ends'of the fuse strip are secured. An exteriorl threaded plug is received on and prefers ly permanentl secured to each contact blade at the mid e thereof. Said plug has the threaded body-portion 16 andthe enlarged annular flanged inner end-portion 17 adapted slidably to be received within the ring 12 and vdiametrically opposed peripheral notches or .fguide-ways`17 are formed in the periphery vof said end-pprtion adapted to receive the ides 12 of said rings 12 whereby the plug ,with the outer end wall 18 having the elon Lgatedfslot 19 therethrough and the reduced end portion 14* of the contact blade is extended therethrough up to the shoulder formed at the junction of the reduced and outer portions of the contact blade. The contact blade may be a tight friction fit in said slot in the end wall but preferably the plug is permanently secured on the blade by suitable means as by peening the walls of the slot into forcible engagement with the contact blade, or soldering.

The fuse is arranged to vent throu h said lugs. For this purpose the plug is ormed tion and the larger interior recess 21` in the end portion 17 thereof. 0

The outer end wall has two diametrically opposed apertures therethrough disposed at rlght angles to the slot 19 and serveas vents for the escape of gas from the casing. The interior recess 20 contains a body of suitable foraminous material 20, as steel wool, asbestos libres, perforated metal discs, and the like which serves to divide the gas into a lurality of small streams and cools the gas. aid recess 20 is closed by the disc 24 which is forced within the(l recess 21 against the shoulder 22 and retained therein by friction and forms the inner end-Wall of` the plug. Said disc has the elongated slot 26 therethrough which is arranged in line with the corres nding slot 19 in the outer end wall; and t e contact blade is also extended throughl said slot. lThis construction provides a rigidA supporting structure forv the blade. f

A .plurality of apertures 27 for gas are formed through sai disc 24; and said apertures are staggered with relation to the corresponding pertures 18* in the end-wall of the plug so that a circuitous gas p n; through the plug is provided. Internally threaded end-caps 28 arei r emovably threaded on the end ferrules. baid caps have the end-walls 28IL which extend be.-

ond the walls of the enclosing casing 10 and iiave the o nings 28" therein; and the threaded bod)e -portions of the vlugs extend through said openings. The e arged inner end-portions of the plugs, however, are of too great a diameter to pass through the openings and consequently the end-caps retain the plugs and contact blades within the casing. Internally threaded locking-nut 29 are removably threaded on the extended bodlyportions of the plugs and serve to draw t e inner ends 17 thereof against the inner faces of the end-walls of the end cap and lock them and their contact blades to the end-caps.

In assembling the fuse, the fusible element l `which includes the blades 14 is extended through the casing, and the guides 12* of the casin are caused to engage the guide-ways 17 o the plugs 16 of the contact blades. The end caps are then screwed on the ferrules and the locking nuts are screwed onthe plugs; and the fusible element will thereby be locked to the casing against rotatmembers are in full view; and the blades are very firmly held in position.y

The dimension, numbers and arran ement of the recesses in the end plugs and a so' the amount and nature.of the coolin material therein contained will be governe according to the capacity of the fuse and 'the service on .which it is to be used.

The arrangement shown is very conven ient in providing any desired character of vent; and the venting will not be affected by the subsequent reloading of the fuse by the user and the jointbetween the plug and end cap can be made practically gas tight.

I claim:

1. In a renewable electric fuse, the combination of a tubular enclosing casing, an exteriorly-threaded ferrule received on its end, said casing having internal uides in an end thereof, an end-cap remova l received on said ferrule having an end-wal inwardly extended beyond the wall of the casing and an opening in its end-wall, a contact blade having a flanged portion with guide ways therein for the uides of the casing and enga able with t e end-wall of the end-cap ai; havin an externally threaded portion extend through the opening in the end-wall of the end-cap, and an internally threaded walls,

loc -nut received o n the threaded portion of sai -intact` blilde t; dirgli and hold tle ilanged rtion t ereo a inst t e end-wallpgf said end-ca andythegieby l0ck said contact blade to sai end-cap. 2. A renewable electric fuse comprising the combination of a tubular enclosing casing, exteriorly threaded ferrules received on the ends of the casing, rings having 1nwardly-directed projections forming ides received in the endsof said casing, en -caps removably received on` said ferrules having end-walls inwardly directed beyond the walls of the casin and openings in the endcontact blades having enlarged flanged portions with guide ways therein for the guides of the casing' and engageable with the end-walls of the end-caps and also having exteriorly threaded portions extended through the openings in the end-walls of said end-caps, and interiorly threaded locking-nuts received on said threaded portions to draw and hold said flanged-portions firmly a ainst said endwalls of said end Caps an thereby lock said contact plugs to said end caps. t

3. A renewable electric fuse comprising the combination of a tubular enclosing casing, exteriorly threaded ferrules received on the ends of the casing, said casing having internal ides in its ends, end-caps removabl received on said ferrules having endwa ls inwardly extended beyond the wall' of the casin and openings in the end-walls, vcontact bla es, externally threaded plugs in which said blades are fixed having enlarged flanged end-portions with guide-ways therein for the guides of the casing and engageable with the end-walls of said end-ca s, said exteriorl threaded portions of sai plugs extended)1 through the openings in the endwalls of said end-caps and exteriorly threaded lockin -nuts received on said plugs to draw an hold the enlarged flanged portions thereof rmly a inst said end-walls of said end-caps and tereby lock said contact blades to said end-caps.

4. A renewable electric fuse having the combination of a tubular enclosing casing, exteriorly threaded ferrules received on the endsof the casing, rin having internal projections forming guises received in the ends of the casing. end-caps removabl received on said ferrules having end-wal s inwardly `extended beyond the wall of the casing and openings in the end-walls, contact- -nuts received on said plugs to draw and hold said4 flanged pori130 tions thereof firmly against the end-Walls of said endcaps and thereby lock said contact blades to said end-caps.

5. In an electric fuse, the combination of a tubular enclosing casing, an exteriorly threaded ferrule received on its end, said casing having internal guides in'an end thereof, an end-cap removably received on said ferrule having an end-wall inwardly extended beyond the wall of the casing andI an opening in its end-wall, a contact blade, a plug having an enlarged flanged end-portion with guide-ways therein for the guides of the casing, a 'reduced externally threaded body-portion, an interior recess in its body-portion and an outer end-wall with an elongated slot therein through which the contact blade is extended, a foraminons body of cooling material received in said recess, the end-wall of said plug having gas vents therein, a disc having an elongated slot through which said contact blade is extended and gas vents therein fixed in the inner end of said. vplug whereby to enclose said foraminous body within the openings in the endwall of said end-cap and an internally threaded, locking-nut received on said plug to draw and hold the flanged portion of said plug rmly in contact with the end-wall of said end-cap and lock the contact blade to said end-cap.

6. A renewable electric fuse having the combination of a tubular enclosing casing, exteriorly threaded ferrules received on the ends of the casing, rin s having internal projections forming guides received in the ends of the casing, end-caps removably threaded on said ferrules having end-walls with openings therethrough, a fusible element comprising a fusible central portion and contact blades at each end, arranged longitudinally within the casing, plug-portions fixed to said contact blades having enlarged inner ends too large to pass through the openings in the end-walls of said endcaps and exteriorl threaded portions extended through said openings, said enlarged portions of said plugs having guide-ways for said guides, and interiorly threaded locking nuts received on the threaded portion of said plugs to lock said contact blades in place with relation With said end-caps.

7. A renewable electric fuse having the combination of a tubular enclosing casing, exteriorly threaded ferrnles received on the ends of the casing, rings having internal projections forming guides received in the ends of the casing, end-caps removabl threaded on said ferrules having end-Wal s with openings therethrough, a fusible element comprising a fusible central portion and contact blades at each end arranged longitudinally within the casing, plug-portions fixed to said contact blades having enlarged inner ends too large to pass ends of the casing, rings having internal ,i

projections forming guides received in the, ends of the casing, end-caps removably 'threaded on said ferrules having end-walls with openings therethrough, a fusible ele,- nient comprising a fusible central portion and contact hlades'at each end arranged longitudinali)r within the casing, plug portions fixed to said contact blades having enlarged inner ends too large lo pass through the openings in the end-walls oi' said end caps and exteriorly threaded portions extended through said openings, said enlarged portions of said plugs having guide-ways for said guides, and nteriorly threaded locking nuts received on the threaded portions of said plugs to lock said contact blades in place with relation to said endcaps, said plugs having interior recesses and end-walls with gas passages therethrough, and bodies of foraminous material received in said recesses.

9. A renewable electric fuse comprising a tubular enclosing casing, a knife-blade fuse terminal having an externally threaded portion, said casing and terminal having cooperating components to prevent rotation of the terminal within the casing, an end cap removably threaded on said casing engageable by said terminal to prevent outward axial movement of saidtern'iinal and a locknut removably threaded on the threaded portion of said terminal to lock said terminaland end cap together.

10. A renewable electric fuse comprising a tubular enclosing casing having an internally projecting end-portion, a fuse terminal, an externally threaded plug fixed thereon engageable with said end-portion, and a lock nut removably, threaded on said plug to engage said end-portion to lock said terminal in said casing.

11. A renewable electric fuse comprising a tubular enclosing casing, a knife blade fuse terminal, said casing and blade having cooperating means to lock the blade in the casing against rotation, and other means including a` lock nut removably threaded on the knife blade to lock said blade against axial movement in said casing.

12. A renewable electric fuse comprising lili) a tubular enclosing casing, a knife-blade fuse terminal having an externally threaded portion, Said casing and terminal having complementary portions engageable to restrain the terminal from rotary movement and outward axial movement in the casing, and a lock-nuty removably threaded on the threaded portion of said terminal engageable with said casing to lock said terminal to said casing.

i3. A fusible element for a renewable enclosed electric fuse of the cartridge type comprising a fusible strip, knife-blade fuse terminals removably attacned to the ends of said 'fusible strip, plugs fixed to said blades having externally-threaded bodyaortions and inner enlarfred end-portions formed with guide-Ways, said plugs also having iniai gas-cooling chambers end-Walls staggered gas passages therein.

. fusible element for a renewable enelecti'ic fuse of the *idge type .ising fusible strip, knife-blade fuse inals removably attached to the ends of mible strip` plugs fixed to said blades having ei-.t-ernall)Y threaded body-portions inner enlarged end-portions formed with guide-wa s, said plugs also having internal gas-coo ing chambers and end-walls with staggered gas passages therein and foraminousfbodies of gas-cooling material received within said chambers.

l5. A knife-blade fuse terminal for a renewable enclosed electric fuse of the cartridge type having a plug through which said knife-blade is passed and to which said plug is permanentlyv attached, said plug being formed with an inner gas cooling chamber and end-Walls disposed on said knife blade and formed with gas passages therethrough.

18. A knife-blade tuse terminal for a renewable enclosed electric fuse having a plu through which said knife-blade is passed and to which said plug is permanently attached, said plu having an inner recess and a perforated ene wall integral with the body of the plug, a perforated disc diseised on knife-blade in said plug-3f and l Ywall of said plug'T -`received in said gi rhereo'lf`,` nave lng an en;N 

